A Multi-fiber Model Of Optic Nerve Activated By Different Electrical Stimulations

The visual prosthesis is an artificial organ to restore functional vision forblind patients and has attracted worldwide interest at present. After processingthe acquired image, the encoded pulses were transferred through microelectrodearray to stimulate the visual system and elicit phosphenes. Our group proposed avisual prosthesis based on optic nerve stimulated by a penetratingmicroelectrode e array.The purpose of this research is to study the response properties of the opticnerve fibers under electrical stimulation by the way of mathematical modeling.Based on the previous single fiber model of optic nerve, we completed themulti-fiber model to study effects of different external electrical fields on theexcitability of the optic nerve fibers. Simulation results could be a theoreticalbasis to design electrode and electrical stimulation parameters of the optic nervevisual prosthesis.The paper mainly included three parts:1. Construct a finite element modelto simulate the external electrical field produced by a single electrode penetrating into optic nerve in COMSOL Multiphysics.2. Implement themulti-fiber model in NEURON and apply the external electrical field computedby COMSOL to the multi-fiber model.3. Study the response properties of opticnerve fibers by changing stimulation waveforms and electrode structure.The innovation of this paper include：1. Model the optic nerve in COMSOLbased on its anatomical structure and electrophysiological characteristics.2. Byimplementing the multi-axons model, we study the excitability of optic nervefibers under different stimulation conditions according to the changes of shapeand size of excited area, but not a single axon. The results provided a theoreticalguidance for the design of the electrode and stimulus strategies of the opticnerve visual prosthesis.